Ever looked at a best-selling book by a celebrity and thought ‘How on Earth did they have the time to write that?!’ Well, a not so well-kept secret is a lot of stars don’t write their own books.

Enter ghostwriters: authors who will transfer the words of the A-list, sports stars and influencers to the page. Ghostwriting has been happening for hundreds of years, but the phrase was only coined in 1921 by an American sports agent who wanted authors to write for his baseball players.

Fast forward to now, and the world’s fastest-selling non-fiction book – Prince Harry’s Spare – was written by Pulitzer-prize winning journalist J.R. Moehringer. And Britney Spears’ long-anticipated memoir The Woman In Me – released after she finally broke free of her conservatorship – was, according to The New York Times, put together by a team of three writers.

But it’s not just the A-list who are filling the shelves with ghostwritten books. Your favourite online celebs are, too – with sales that are translating in real life. ‘I think when people think about ghostwriting, they assume it’s going to be Hollywood celebs,’ one ghostwriter – who has worked with numerous UK celebs, but wishes to remain anonymous – tells Grazia, ‘but if you think about big books that are selling in your local book shop, it’s reality stars and influencers.’

And she notes that these books ‘are not always autobiographies, they’re sometimes a mix of memoir and advice.’ A recent bestseller to do this is Pete Wicks’ Never Enough, which touches on themes of mental health and toxic masculinity.

When it comes to finding the perfect ghostwriter, just like a dating agency, she tells us that a ‘variety’ of writers meet the celebrities, either on Zoom or in real life – so all involved can ensure it’s a right match. ‘It does actually work,’ she says. ‘I’ve generally written for celebrities who are interesting and likeable, and that’s why they’re successful.’

The deadlines for writers to put together these books is usually tight, with only a few months to write the manuscript. ‘It’s an intimate, but temporary relationship,’ she says, ‘but they do trust you – they tell you stuff.’

In terms of how it all ends up on the page, the ghostwriter says a plan for the project is thought up by the celebrity, publisher or ghostwriter, then the ghostwriter will interview the celeb numerous times, which will then be written up and turned into the book.

Our ghostwriter says that she’s typically contracted to spend 20 hours with a celebrity – though she says this doesn’t always happen due to hectic schedules. ‘You generally get more time [with the celeb] at the end when they realise the deadline is looming, but that’s when you’re busiest writing.’

Ghostwriters tend to be paid flat fees – which our ghostwriter says is usually around £10,000, depending on word length – whereas celebrities will ‘get something upfront, but if they sell past a certain amount, they’ll go into royalty territory, where they’ll get extra money.’

And of course, as the book is under the celebrity’s name, they get the final say as to whether they’re happy with it. It means ghostwriters are very different to journalists – they won’t include anything the celebrity doesn’t want them too, and our ghostwriter says that she’s happy to take things out which they might have said earlier. ‘I’m not trying to catch them out,’ she says, ‘as when I write things I’ll write them in a way which protects them.’

It’s not just self-help and memoir either, the practise looks like it’s becoming more common in fiction writing. Does anyone remember Kendall and Kylie Jenner’s sci-fi young adult book Rebels? (Obviously, the two main characters are sisters.) Or Millie Bobby Brown’s WW2 set romance book, Nineteen Steps? In both cases, it wasn’t a huge secret that someone else had written the book. Maya Sloan, who wrote the Jenners’ book, said she spent time behind-the-scenes with the sisters during a fashion week, and Brown thanked her ghostwriter Kathleen McGurl in an Instagram post.

But there’s a lot of celebrity fiction which isn’t so clear. And the Society of Authors – the UK’s largest trade union of authors, illustrators and translators – has called for ghostwriters to receive more recognition (particularly when it comes to celebrity books aimed at children).

The ghostwriter we’ve spoken to hasn’t written fiction for celebs, but she thinks the SOA has a point, and fiction should be credited as double byline – because writing a story demands more from the ghostwriter. ‘Memoirs and non-fiction are often based on people’s lives, experiences and thoughts, but a lot of fiction is also being written by ghostwriters – not all – so it can be quite confusing, especially if you’re a reader who’s not in the publishing industry.’

Whatever the type of book, in the acknowledgements is where the ghostwriter is usually thanked by the celebrity – and it isn’t always clear that it’s written by a ghostwriter. ‘It will phrase it in a way that’s sort of like: thanks to so and so for helping me get my thoughts together,’ she says. Though there are exceptions: Mariah Carey named her ghostwriter Michaela Angela Davis on her memoir.

Maybe, in the future, we’ll know more about the people who are actually writing the words behind the scenes. ‘I think the secrecy around ghostwriters feels a bit out of date at this point, because we’re in this world of authenticity, and influencers especially are prized for their original voices,’ our ghostwriter says. ‘It makes sense for them to be [like] it’s all my thoughts and creativity, but I had someone help me get it down on paper as I’m really busy, and I needed help with structure and telling it in 60,000 words.’ But, until honesty becomes more common, you can always check the acknowledgements.